(394a) Combination of Electroosmotic Flow and Dielectrophoretic Trapping of Particles in a Contactless-Dielectrophoretic Device

Microfluidics is a rapidly growing field that offers great potential for many biological and analytical applications. There are important advantages that miniaturization has to offer, such as portability, shorter response times, higher resolution and sensitivity. There is growing interest on the development of microscale techniques. Among these, electrokinetic phenomena have gained significant importance due to their flexibility for handling bioparticles. Dielectrophoresis (DEP), the manipulation of particles in non-uniform electric fields due to polarization effects, has become one of leading electrokinetic techniques. DEP has been successfully employed to manipulate proteins, DNA and a wide array of cells, form bacteria to cancer. Contactless-DEP (cDEP) is a novel dielectrophoretic mode with attractive characteristics. In cDEP nonuniform electric fields are created by using insulating structures and external electrodes that are separated from the sample by a thin insulating barrier, this prevents bioparticle damage, and makes cDEP a technique of choice for many biomedical applications. In this study, a combination of cDEP generated with AC potentials and electrokinetic liquid pumping generated with DC potentials is employed to achieve highly controlled and selective particle trapping and manipulation, allowing for lower applied potential than those used in traditional insulator-based DEP, and making for a simpler system that does not require the use of an external pump. This is the first demonstration of electrokinetic (EK) pumping in which the driving electrodes are not in direct contact with the sample fluid. Multi-physics simulations were used to aid with the design of the system and predict regions of particle trapping. Results show the advantages of combining AC-cDEP with DC EK liquid pumping for dynamic microparticle trapping, release and enrichment.